We previously found that daidzein decreased food intake in female rats. To understand the mechanism of anorectic action of dietary daidzein, it is necessary to determine distributions of daidzein and S-equol, a metabolite of intestinal bacterial conversion from daidzein, in the body. In the present study, we measured the concentrations of daidzein and S-equol in serum and bile in sham-operated and ovariectomized female rats fed a diet containing 150 mg/kg daidzein for 7 days. Dietary daidzein increased serum and bile concentrations of S-equol to far higher levels than those of daidzein. S-equol concentration was more than several hundred fold-higher in bile than in serum, regardless of ovariectomy. Moreover, to investigate whether accumulation of S-equol is facilitated by efficient enterohepatic circulation during continuous intake of daidzein and S-equol, female rats were fed diet containing daidzein or S-equol (both 150 mg/kg), or control diet for 1, 2, 3, or 5 days. Dietary daidzein significantly increased serum and bile concentrations of S-equol in a time-dependent manner, but not those of daidzein. These results indicated that substantial proportion of dietary daidzein was converted to S-equol, which underwent efficient enterohepatic circulation and predominantly accumulated there.

中文翻译：

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在有或没有卵巢切除术的雌性大鼠中，膳食黄豆苷元诱导的肝牛肝循环中S-雌马酚的积累远高于黄豆苷元。

我们先前发现大豆苷元降低了雌性大鼠的食物摄入量。要了解膳食大豆苷元的厌食作用机理，有必要确定大豆苷元和S-牛尿酚（黄豆苷元经肠道细菌转化后的代谢产物）在体内的分布。在本研究中，我们测量了以假手术和卵巢切除的雌性大鼠喂食含150 mg / kg大豆苷元的饮食7天后血清和胆汁中大豆苷元和S-牛尿酚的浓度。膳食黄豆苷元使S-雌马酚的血清和胆汁浓度增至远远高于黄豆苷元。不论卵巢切除术如何，胆汁中S-牛尿酚的浓度都比血清中高数百倍。此外，为了研究在连续摄入大豆苷元和S-雌马酚期间是否通过有效的肝肠循环促进S-雌马酚的积累，对雌性大鼠饲喂了含有大豆苷元或S-雌马酚的饮食（均为150 mg / kg），或对照饮食分别为1、2 ，3或5天。膳食大豆苷元以时间依赖性方式显着增加了S-牛尿酚的血清和胆汁浓度，但大豆苷元却没有。这些结果表明，膳食黄豆苷元的大部分被转化为S-牛尿酚，其经历了有效的肠肝循环并主要在其中积累。